论文部分内容阅读
今年我教小学四年级数学,也是我第一次教新教材的四年级课程。在本地区小学期末检测中有这样一道试题:甲乙丙三人同时来到某理发店理发,但是理发店里只有一位师傅,根据实际情况,甲理发需要8分钟,乙理发需要10分钟,丙理发需要15分钟,理发师傅将怎样安排这三个人的作业顺序,才能使他们三人等候的时间总和最少?最少是多少分钟?我们班的学生都是这样做的:按照先甲再乙最后丙的顺序安排,甲等候了0分钟,乙等候8分钟(等甲理发完再轮到乙,因此乙等候时间为8分钟),丙等候18分钟(同理,丙要等甲和乙理发完了才轮到自己,所以丙的等候时间为8+10=18分钟)。他们等候时间总和为0+8+18=26分钟。可是阅卷老师说我们错
This year I teach the fourth grade mathematics in primary school, but also my fourth grade teaching new teaching materials. In the local primary school end of the test there is such a test: A and B three people came to a barber shop haircut at the same time, but the barber shop only one master, according to the actual situation, A haircut needs 8 minutes, B haircut takes 10 minutes, C Haircut for 15 minutes, how will the hairdresser arrange the work order of these three people, so as to make the sum of the three people waiting for them at least? What is the minimum number of minutes? The students in our class all do the following: A waiting for 0 minutes, B waiting for 8 minutes (waiting for the hair after another hair B, so B waiting time for 8 minutes), C waiting for 18 minutes (empathy, C and B to wait until the hair finished Turn yourself, so C’s waiting time is 8 + 10 = 18 minutes). The sum of their waiting time is 0 + 8 + 18 = 26 minutes. But the marking teacher said we were wrong